An editor should provide a user property for the data it edits. QItemDelagates can then access the property using Qt's meta-object system to set and retrieve the editing data. A property is set as the user property with the USER keyword:

If the editor does not provide a user property, it must return the name of the property from valuePropertyName(); delegates will then use the name to access the property. If a user property exists, item delegates will not call valuePropertyName().

Returns the name of the property used to get and set values in the creator's editor widgets.

When implementing this function in subclasses, you must ensure that the editor widget's property specified by this function can accept the type the creator is registered for. For example, a creator which constructs QCheckBox widgets to edit boolean values would return the checkable property name from this function, and must be registered in the item editor factory for the QVariant::Bool type.